Removing sulfur compounds



Patented June 13, 1950 REMOVING SULFUR COIVIPOUNDS Charles F. Feasley, Woodbury, N. J., assignor to Socony-Vacuum Oil Company, Incorporated, a corporation of New York No Drawing.

Application March 14, 1946,

Serial No.'654,516

9 Claims.

This invention relates to the removal of sulfur compounds from organic water-immiscible liquids, especially hydrocarbon oils and, more particularly, to the removal of sulfur compounds from petroleum and petroleum fractions.

The prior art has sought to solve the problem of removing sulfur compounds from organic water-immiscible liquids and particularly petroleum and its fractions by many methods. For example, mercaptans have been removed from light products by extraction with alkaline reagents, sulfur compounds have been removed from crudes and reduced crudes by treatment with sulfuric acid and other acid mixtures and acids such as hydrogen fluoride. Sulfur has likewise been removed from crudes and reduced crudes by contact with a catalyst such as bauxite at elevated temperatures.

Other methods for removing sulfur from petroleum are illustrated by the following methods involving condensation of the sulfur compounds. For example, U. S. Patent No. 1,950,735 describes a process in which the stock is treated with sulfuric acid at the rate of about 6 pounds of concentrated acid per barrel (42 gallons) after which the stock is neutralized and washed in the conventional manner. The washed stock is then treated wtih about 2 per cent by weight of a ketone such as acetone, propanone, butanone, methyl ethyl ketone and the like in the presence of a Friedel-Crafts agent such as zinc chloride or aluminum chloride to remove some of the sulfur compounds present in the acid treated oil as condensation products. A similar process is described in U. S. Patent No. 1,974,311. This process involves treating cracked petroleum vapors with 2 per cent formaldehyde in the presence of about one pound of zinc chloride per barrel to lower the sulfur content and to lessen the tendency of the stock to form gum. U. S. Patent No. 1,114,045 describes the treatment of tar with aqueous formaldehyde at the rate of 1.5 gallons of aldehyde to 2,000 gallons of tar to remove carcinogenic materials.

U. S. Patent No. 2,098,059 discloses that the color, gum-forming tendency and sulfur content of cracked fuel oil can be improved by treating the vapors with one pound of hydrogen halide and one pound of formaldehyde per barrel of finished gasoline in the presence of copper turnings. U. S. Patent No. 1,104,906 teaches that petroleum stock can be improved by treatment with steam and formaldehyde and then with hydrogen. U. S. Patent No. 2,060,091 describes the distillation of petroleum products in the presence of adsorbent material such as fullers earth at 550 degrees to '750 degrees Fahrenheit to re- 1: move sulfur. Furthermore, it is known that sulzinc chloride or aluminum chloride.

It will be noted that with the exception of the process described in U. S. Patent No. 2,060,091 and that described in British Patent No. 560,225 (1944) all of the prior art processes involve the use of a catalyst or condensing agent which cannot be recovered and re-used or can only be recovered and re-used at a disproportionate expense. 'In distinct contrast the present invention provides a means for removing sulfur compounds from water-immiscible organic liquids, and particularly hydrocarbon oils, by forming condensation products from the sulfur compounds in the presence of a catalyst which can be recovered and re-used. In contrast to the processes described in U. S. Patent No. 2,060,091 and British Patent No. 560,225 (1944) desulfurization by the present method is obtained without substantial cracking whereas these prior art methods involve the use of conditions under which considerable cracking takes place.

It is an object of the present invention to provide a means for removing sulfur compounds, including thiophene, from water-immiscible organic liquids by condensing said sulfur compounds with a carbonyl compound in the presence of a condensation agent comprising alumina-silica clays particularly of the Montmorillonite type or synthetic alumina-silica cracking catalysts containing about 7 per cent to about 15 per cent alumina and separating the condensation products so formed.

In general, the present process is useful for removing sulfur compounds capable of forming condensation products in which two or more molecules of cyclic sulfur compound are joined through a methylene group or a divalent carbon having attached thereto two alkyl, aralkyl, aryl, alkaryl or hydrogen groups which may be the same or different. That is to say, using thicphene for purposes of illustration, although other cyclic sulfur compounds react in a similar manner, this cyclic sulfur compound may be represented as reacting according to the following equation:

Use.

Where n is a small whole number.

This may be expressed more generally by the following equation where R=a cyclic sulfur compound:

where n is a small Whole number, R and R are hydrogen or alkyl, aralkyl, aryl or alkaryl. In the past, condensations of this type have only been carried out employing acid catalysts or catalysts of the Friedel-Crafts type. Such catalysts as these latter have the disadvantage that they are very difi'icult to separate and almost impossible to recover for re-use. In addition, most of the prior art catalysts for similar condensations produce side reactions which are undesirable because of the resulting loss of valuable hydrocarbon stock.

The catalysts of the present invention, on the other hand, are cheap initially, are easily recovered and regenerated and, for the most part, lead to a desulfurized product of improved color. In addition to the activated clays of the Montmorillonite type, fresh burnt Attapulgus clay, silica gel and synthetic alumina-silica clays containing about '7 to about 15 per cent alumina may be used.

The novel catalyst or condensation agent is a solid adsorbent contact mass such as clays of the activated Montmorillonite type, fresh burnt Attapulgus clay, silica gel, synthetic alumina-silica gel catalysts containing about 7 per cent to about 15 per cent alumina, powdered cracking catalyst which is a base exchanged silica-alumina catalyst containing about 7 per cent to about 15 per cent alumina. As those skilled in the art know all of the foregoing catalysts have been used in the catalytic cracking of hydrocarbons. The condensation agent is used preferably in finely-divided or powdered form. Illustrative of the clays of the Montmorillonite type which have provided satisfactory results is a non-swelling crystalline rather than amorphous bentonite clay which has been activated by an acid treatment in a manner well known to those skilled in the art to give a composition approaching Al2Si4Oio(OH)z-nHz0 and available to the art under the trade name.

Super Filtrol. Activated clay of the Montmorillonite type, Attapulgus clay, silica gel, and synthetic alumina-silica gel catalysts containing about '7 to about 15 per cent alumina are all cracking catalysts which have been classed in the past as solid, inorganic oxide, absorbent, contact materials.

Amon the advantages of the process of the present invention for desulfurization is the small loss of hydrocarbons resulting therefrom in comparison with the losses of hydrocarbons in other prior art processes. Furthermore, the resins and viscous oils formed in the process are of industrial value as plasticizing agents, rubber softening agents, cable oils, insulating oils, insecticides and the like.

The relative amount of catalyst or condensation agent may vary over a wide range of about to.

about 25 per cent by weight of the oil or even more. The relative amount of carbonyl compound used depends upon the amount of sulfur compounds such as thiophene present in the water-immiscible organic material.

Formaldehyde in its various forms is the preferred carbonyl compound but the process provides satisfactory results when using ketones such as acetone, propanone, aryl ketones, alkyl-aryl ketones and aldehydes such as acetaldehyde, propanaldehyde, benzaldehyde and the like. In general, aliphatic aldehydes and ketones having not more than seven carbon atoms exclusive of the carbonyl carbon, mononuclear aromatic aldehydes and ketones having not more than seven carbon atoms in the alkyl chain and alkyl-aryl ketones such as acetophenone in which the alkyl group contains not more than seven carbon atoms may be used.

While distillation is the preferred method for separating the condensation products from the desulfurized stock, other methods of separation, such as adsorption, absorption, extraction and the like, may be employed.

In the case of stocks containin thiophene and similar very reactive materials, the condensation products with formaldehyde are actually solvent insoluble because of their high molecular weight and complex nature and may be partially removed along with the clay by a simple filtration.

The sulfur-containing stocks which may be treated by the novel process are, particularly, those petroleum stocks which contain thiophenic or other aromatic types of sulfur compounds. The present process is a particularly satisfactory method for preparing thiophene-free benzene.

Illustrative, but not limiting, of the application of the principles of the present invention to the desulfurization of water-immiscible organic liquids are the following examples.

Example I A synthetic blend (500 cubic centimeters or 432 grams) of pure thiophene and relatively sulfurfree benzene (0.004 per cent sulfur by the lamp method) containing 0.297 per cent total sulfur was treated at 360i10 F. for 6 hours with 5 grams of trioxymethylene and grams of activated clay of the Montmorillonite type to give, after filtration, extraction of clay with acetone and distillation, nearly a quantitative yield of thiophene-free benzene containing 0.002 per cent total sulfur by the lamp method.

Example II A charge identical with that used in Example I was made up and held at about 340:10" F. for 6% hours and worked up as described before to give 371.5 grams (86 per cent recovery) of thiophone-free benzene containing 0.003 per cent sulfur by the lamp method.

Example III Fifty grams of an activated clay of the Montmorillonite type and 30 grams of paraformaldehyde were allowed to react with 200 grams of Gach Saran gas oil (0.8 per cent sulfur) for 12 hours at C. (atmospheric pressure). The

' clay and unreacted paraformaldehyde were re- (42.5 per cent desulfurization) leaving behind 7.5 grams of reddish-brown, tacky resin.

The original gas oil before treatment had the following properties:

Lamp sulfur"; --per cent 0.80 Pour point Q. F 5 Flash point (Pensky Martin) -JF-.. 150 A. P. Lgravity 37.9

A. S. T. M. distillation, F.:

I. B.P 365 5% by vol 390 by v 403 by vol 422 by vol 444 by vol 467 by vol 492 by vol 521 by vol 548 by vol 572 by vol 602 E.P 630 Per cent recovery 98.0 Per cent residue 2.0

Example IV Five hundred cubic centimeters (455 grams) of Santa Maria gas oil (3.74 per cent sulfur) was allowed to react with 20 grams of paraformaldehyde and grams of an activated clay of the Montmorillonite type for 5% hours at 350 F. After working up in the manner of Example III, 333 milliliters or 310.1 grams (68.2 per cent recovery) of recovered gas oil containing 3.4 per cent sulfur (9.1 per cent desulfurization) was obtained, leaving behind 94.8 grams of a viscous oil residue containing 4.74 per cent sulfur (91 per cent of material accounted for in solvent soluble form).

This gas oil before treatment had the following properties:

Example V Slaughter Duggan gas oil (600 cubic centimeters or 510 grams) containing 1.6 per cent sulfur, 124.5 grams of Super Filtrol and 75 grams of trloxymethylene were charged into a one liter. stainless steel Aminco rocking bomb and held at 370 F. to 400 F. for 5 hours under the pressure of the system. At the end of this time the bomb contents were flushed out with acetone, filtered from the clay and distilled into the fol- This accounts for 365 grams of recovered desulfurized material having an average of 0.95 per cent sulfur (40.7 per cent desulfurization). Including solvent soluble resins (56 grams), 421 grams or 82.6 per cent of the material was recovered.

The original gas had the following properties:

From the foregoing it will be appreciated that temperatures of about 340 to about 450 de ees Fahrenheit can be employed in batch operations using residence times of the order of 0.75 to 12 hours. This process may also be carried out in a continuous manner with conditions of temperature and residence time such that substantial cracking does not occur.

I claim:

1. A method of desulfurizing a mixture of hydrocarbons containing organic sulfur compounds condensible with carbonyl compounds which comprises contacting a, mixture of hydrocarbons containing cyclic organic sulfur compounds with formaldehyde in the presence of a catalyst consisting of activated clay at a temperature of about 340 to about 450 F. for a period of about 0.75 hour to about 12 hours, and separating a mixture of hydrocarbons of reduced sulfur content.

2. A method of desulfurizing a mixture of hydrocarbons containing organic sulfur compounds condensible with carbonyl compound which comprises contacting a mixture of hydrocarbons admixed with cyclic organic sulfur compounds condensible with organic carbonyl compounds with formaldehyde in the presence of a catalyst consisting of a solid, inorganic oxide, absorbent contact material at a temperature of about 300 to about 450 F. for about 0.75 hour to about 12 hours, and separating a mixture of hydrocarbons of reduced sulfur content.

3. A method of desulfurizing a mixture of hydrocarbons containing organic sulfur compounds condensible with carbonyl compounds which comprises contacting a mixture of hydrocarbons lowing fractions: 65 and organic sulfur compounds condensible with n o v1 Wt Ml API P 0 tP 0 t ange 0. O- El 011 61 en out (Reduced Rangflm cc. Wt. Gravity Sulfur Desull.

Press. mm.)

1 88104464 215-252" 0. (419-485F.)-. 104 as 40.8 0. 56 05.0 2 14640-245; 252445C.(485-832F.). 343 282 352 35.1 1.01 33.1 Residue-Solid Resin 50 001 4.7a

1 Ring and ball melting point 222 F.

organic carbonyl compounds with a carbonyl compound having. the formula in which R is selected from the group consisting of alkyl and aryl radicals and R is selected from the group consisting of hydrogen, alkyl radicals and aryl radicals in the presence of a catalyst consisting of a solid, inorganic oxide, absorbent contact material at a temperature of about 300 to about 450 F. for about 0.75 hour to about 12 hours, and separating a mixture of hydrocarbons of reduced sulfur content.

4. A method of desulfurizing a mixture of hydrocarbons containing organic sulfur compounds condensible with carbonyl compounds which comprises contacting a mixture of hydrocarbons and organic sulfur compounds condensible with organic carbonyl compounds with a carbonyl compound having the formula in which R is selected from the group consisting of alkyl and aryl radicals and R is selected from the group consisting of hydrogen, alkyl radicals and aryl radicals in the presence of a catalyst consisting of a solid, inorganic oxide, absorbent contact material at a temperature of at least 300 F. but below the temperature at which said hydrocarbons are'cracked in the presence of said absorbent contact material as the sole catalyst and separating a mixture of hydrocarbons of reduced sulfur content.

5. A method of desulfurizing petroleum hydrocarbons admixed with organic sulfur compounds which comprises contacting a mixture of petroleum hydrocarbons and organic cyclic sulfur compounds with a carbonyl compound having the formula in which R is selected from the group consisting of alkyl and aryl radicals and R is selected from the group consisting of hydrogen, alkyl radicals and aryl radicals in the presence of a catalyst consisting of a solid, inorganic oxide, absorbent contact material at a temperature of at least 300 but less than the temperature at which said hydrocarbons are cracked in the presence of said absorbent contact material as the sole catalyst and separating a mixture of petroleum hydrocarbons of reduced sulfur content.

6. The method of desulfurizing petroleum hydrocarbons admixed with organic sulfur compounds as described and set forth in claim 19 wherein the mixture of hydrocarbons and organic sulfur compounds has an initial boiling point of at least 350 F. and the solid, inorganic oxide, absorbent contact material is activated clay.

'7. The method of desulfurizing petroleum hydrocarbons admixed with organic sulfur compounds as described and set forth in claim 19 wherein the mixture of hydrocarbons and organic sulfur compounds has an initial boiling point of at least 350 F., the carbonyl compound is formaldehyde, the solid, inorganic oxide, absorbent contact material is activated clay and th'eperiod of contact is not greater than about 12 hours.

8. A method of producing thiophene-free benzenefrom benzene admixed with thiophene which comprises contacting benzene admixed with thiophene with a, carbonyl compound having the formula.

\C=O R/ in which R is selected from the group consisting of alkyl radicals and aryl radicals and R is selected from the group consisting of hydrogen, alkyl radicals and aryl radicals in the presence of a catalyst consisting of a solid, inorganic oxide, absorbent contact material as the sole catalyst at a temperature of at least 300 F. but less than the temperature at which benzene is cracked in the presence of said contact material, and separating benzene substantially free from thiophene.

9. A method for producing thiophene-free benzene from benzene admixed with thiophene which comprises contacting benzene admixed with thiophene with formaldehyde in the presence of a catalyst consisting of a solid, inorganic oxide, absorbent contact material as the sole catalyst at a temperature of at least 300 F. but less than the temperature at which benzene is cracked in the presence of said contact material, and separating benzene substantially free from thiophene.

CHARLES F. FEASLEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,919,722 I-lyman July 25, 1933 1,919,723 Hyman July 25, 1933 2,035,123 Fulton Mar. 24, 1936 2,104,956 Stern et al Jan. 11, 1938 2,114,121 Bender Apr. 12, 1938 2,200,763 Anderson et a1. May 14, 1940 2,232,971 Records et a1 Feb. 25, 1941 2,247,148 Burk June 24, 1941 2,382,184 Thompson Aug. 14, 1945 FOREIGN PATENTS Number Country Date 211,239 Germany June 29, 1909 OTHER 'REFERENCES Fulton et al., Production of Petroleum Resins, Ind. 81 Eng. Chem., Mar. 1940, pages 304-307.

Certificate of Correction Patent No. 2,511,251 7 June 13, 1950 CHARLES F. FEASLEY It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 5, line 6, for the numeral 5 read 5; column 7, line 61, and column 8, line 3, for the claim reference numeral 19 read 5 and that the said Letters Patent should be read as corrected above, so that the same may conform to therecord of the case in the Patent Olfice. Signed and sealed this 27th day of February, D. 1951.

THOMAS F. MURPHY,

Assistant Commissioner of Patents. 

4. A METHOD OF DESULFURIZING A MIXTURE OF HYDROCARBONS CONTAINING ORGANIC SULFUR COMPOUNDS CONDENSIBLE WITH CARBONYL COMPOUNDS WHICH COMPRISES CONTACTING A MIXTURE OF HYDROCARBONS AND ORGANIC SULFUR COMPOUNDS CONDENSIBLE WITH ORGANIC CARBONYL COMPOUNDS WITH A CARBONYL COMPOUND HAVING THE FORMULA. 